title: How to multiply a matrix of normal equations by an arbitrary vector using FFT.
abstract: This paper describes a novel algorithm for multiplying a matrix of normal equations by an arbitrary real vector using the fast Fourier transform technique. The algorithm allows full-matrix least-squares refinement of macromolecular structures without explicit calculation of the normal matrix. The resulting equations have been implemented in a new computer program, FMLSQ. A preliminary version of the program has been tested on several protein structures. The consequences for crystallographic refinement of macromolecules are discussed in detail.
authors.affiliation: V. A. Engelhardt Institute of Molecular Biology, 32 Vavilova Street, 119991 Moscow, Russian Federation. strokop@gmail.com
authors.forename: Boris V
authors.initials: BV
authors.lastname: Strokopytov